Such mufflers are frequently used on air-powered apparatus for smoothing out pressure surges produced when air is suddenly let off from part of the apparatus into the outside atmosphere with the production of undesired noise. In this respect, the damper cartridge has the function of turning the more or less directed, powerful jet of compressed air into a diffuse air flow at a low speed. Such mufflers may be matched or geared to the amount of energy to be dissipated or to the surge characteristics of the exhaust from the pneumatic apparatus, with which the muffler is joined, by having different degrees of porosity in the cartridge so that there is a different choke property.
This sort of matching of the properties of the muffler to compressed air-powered apparatus makes it on the one hand necessary for different sorts of damper cartridges to be kept in stock and furthermore, even so, the properties of the choke of the muffler may not be steplessly adjusted to the needs of the pneumatic apparatus.